This application claims the priority of German application 197 54 736.2, filed in Germany on Dec. 10, 1997.
The invention relates to an intake port for an internal-combustion engine. Especially preferred embodiments relate to an intake port for an internal-combustion engine which has a combustion space which is at least partially constructed in a cylinder head and which, by way of at least one valve-controlled inlet duct leading into its roof section, is acted upon with air or with a fuel air mixture, the inlet duct constructed in the cylinder head having a more curved section facing the combustion space and a less curved section away from the combustion space, and changing into an intake connection piece adjoining the cylinder head, which intake connection piece, together with the inlet duct forming the intake port and being connected with the intake system, and having a guiding device arranged in the intake port and having an adjustable guiding section.
An intake port of this type is described, for example, in German Patent Document DE 44 37 279 A1 and is composed of an inlet duct constructed in the cylinder head and of an intake connection piece flanged to the cylinder head, which intake connection piece is connected with the intake system of the internal-combustion engine. In the intake connection piece, a receiving device for an injection nozzle is constructed whose fuel jet is directed into the inlet duct. Furthermore, a guiding device with a swivellable guiding section is arranged in the intake connection piece, which guiding section is constructed on the side of the guiding device facing away from the cylinder head. This guiding device is arranged such in the intake connection piece that it projects into the entrance area of the inlet duct. In addition to the defined port geometry, this guiding device has the purpose of causing, in the case of a low engine load--idling and partial load--a targeted tumble in the combustion space. However, such guiding devices have the disadvantage that they have a throttling effect at higher rates of air flow in the nominal output range and thus counteract an optimal port construction for the nominal output range. Furthermore, in the case of such intake port geometries, detachments of the flow on the port section inside the curvature will occur in the area of the more curved inlet duct section so that this also has a disadvantageous influence on the mixture preparation in the nominal output range.
With respect to the above, it is an object of the invention to improve an intake port of the above-mentioned type for an internal-combustion engine such that, at low air rates of air flow in the idling and partial load range, the mixture preparation is improved by the targeted tumble generating in the combustion space and simultaneously a higher and more uniform rate of air flow in the nominal output range of the internal-combustion engine is ensured.
According to the invention, this object is achieved by providing that the guiding device is arranged in the inlet duct and, by means of its area close to the combustion space, reaches at least approximately into the more curved section of the inlet duct.
By the arrangement of the guiding device in the inlet duct and the dimensioning of the guiding device into the more curved section of the inlet duct close to the combustion space, as a function of the position of the adjustable guiding section, a targeted tumbling formation can be caused as well as a stabilizing of the flow at higher rates of air flow. Particularly at high rates of air flow in the normal output range, this arrangement of the guiding device contributes to a stabilizing of the flow by way of the port cross-section and can furthermore counteract separations of the flow at the port section on the inside of the curvature. By means of such an arrangement of the guiding device, an improvement of the mixture preparation can therefore be achieved along almost the whole usage range of the internal-combustion engine, during idling and in the partial load range, a combustion-promoting tumbling formation being promoted and, at higher rates of air flow in the nominal load range, a targeted flow and a high rate of air flow being achieved.
The generating of a tumbling in the combustion space for improving the mixture preparation during idling and in the partial load range becomes particularly effective if the adjustable guiding section of the guiding device is constructed on the part of the guiding device close to the combustion space. As a result, particularly in the more curved section of the inlet duct, an effective diversion or deflection of the air flow can be achieved, without any weakening of the flow effect caused by the guiding device by disturbing influences from the port geometry.
By the construction of the guiding device as a baffle and the adaptation of this baffle to the course of the curvature of the inlet duct in the flow direction, particularly for high rates of air flow, a particularly effective stabilizing of the flow can be achieved along the whole port cross-section and particularly at the port section on the inside of the curvature.
A particularly advantageous construction of the guiding device is achieved for multi-cylinder internal-combustion engines if the adjustable guiding section is operated by means of a swivelling axis or swivelling shaft penetrating the inlet duct, and this swivelling axis or swivelling shaft is arranged in parallel to the longitudinal course of the internal-combustion engine. By means of this arrangement, the swivelling axis or swivelling shaft can be constructed such that, in one piece, it penetrates the respective inlet ducts situated behind one another, and the adjustable guiding sections of all cylinders arranged behind one another are therefore adjustable by means of an operating element.
A particularly good tumble formation is achieved if the guiding device divides the inlet duct into an upper and a lower guiding section or into a guiding section on the outside and on the inside of the curvature and, for the tumble formation in the combustion space, the lower guiding section or the guiding section on the inside of the curvature is largely closed.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.